Control of transit stain on wood products

ABSTRACT

The treatment of wood to greatly reduce the in-transit iron staining of same when shipped in commerce by applying thereto prior to shipment an antistatic agent (preferably anionic), or a chemical change inhibitant for iron (preferably a chelating agent for iron), or such antistatic agent in combination with the chemical change inhibitant for iron.

O Hated States Patent l 3,630,763

[72] Inventors William C. Kelso,Jl-; [56] References Cited s s f 1 a i UNITED STATES PATENTS i g fg m 3,422,166 1/1969 Davis 252/389 [21] A 1 No 9550 2,080,299 5/1937 Benning et al. 106/14 [22] Mar 21 1969 2,491,066 12/1949 Wasson e161 106/14 x [45] Patented D l97l 3,133,787 5/1964 106/14 X 3,397,150 8/1968 106/14X [73] Assgnee 32: 2: 1 first many 3,458,300 7 1969 106/14 x Primary Examiner-Julius F rome Assistant Examiner-David A. Jackson g ggT s IRANSIT STAIN 0N WOOD An0meyJohn J. Byrne P OD 1 Claim, 3 Drawing Figs.

ABSTRACT: The treatment of wood to greatly reduce the in- [52] fl 5 2 transit iron staining of same when shipped in commerce by ap- [51 l Int Cl C0 5/08 plying thereto prior to shipment an antistatic agent I i 1 06/1 (preferably anionic), or a chemical change inhibitant for iron 252/389 (preferably a chelating agent for iron), or such antistatic agent in combination with the chemical change inhibitant for iron.

CONTROL OF TRANSIT STAIN ON WOOD PRODUCTS BACKGROUND OF THE INVENTION l. Field of the Invention The invention relates to the treatment of exposed surfaces of either green or dry wood with various chemicals bybrush, dip or spray methods to prevent the in-transit staining of such items when shipped as articles of commerce, especially when shipment is by railway. Thereby, such items are assured of arriving at destination in essentially a mill-bright condition without having to cover them with paper or plastic or enclose them in a boxcar to greatly reduce their discoloration by atmospheric-home stains, such as caused by dirt, dust, soot and/or stain by iron. Such discolorations are greatly reduced by treatment of the wood prior to shipment with a light brush, dip or spray application of compositions of matter comprised of either an antistatic agent, preferably an anionic antistatic agent, or such antistatic agent in combination with a chemical change inhibitant for iron, preferably a chelating agent for iron, or comprised solely of a chemical change inhibitant for iron, preferably a chelating agent for iron.

2. Description of the Prior Art When lumber (or other wood products) is shipped uncovered on open railway cars, it usually arrives at its destination considerably discolored on the exposed surfaces because of atmospheric-home contaminants. Until recently, it was thought that practically all such discolorations caused by such atmospheric-bome contaminants was directly related to such materials as dust, dirt, soot and/or oil droplets contained in the smoke or exhaust of the railway engine. It has now been discovered, however, that the principal staining which occurs during railway and other transit of such materials is caused by iron stain developing on the wood. The iron causing this stain is believed to arise from one or more of the following four sources: (I) from wear on the brakeshoe linings, especially when the train is braking on downgrades; (2) from wear of the wheels on the rails; (3) from iron particles derived from slag from steel mills which is used by many railroads as part of the ballast placed on their railroad beds for stability, drainage, etc., and (4) from residual, prior processing derived iron on the wood.

The iron particles, at least from the first three of the foregoing sources, are apparently furthermore finely divided from constant abrasion beneath the crossties and tie plates, abrasion between adjacent ballast materials and within the surface checks on the exposed surface of the crossties. The result of these abrasive actions is an accumulation of finely divided iron particles from the various sources mentioned, so that the entire surface of the roadbed of the railway is constantly covered with such particles. (The existence of such iron particles was demonstrated by sweeping a railroad bed with a magnet. Large quantities of magnetic iron dust, as well as small slag particles, were picked up by the magnet.)

It is also believed that the aforesaid ground and abraded iron particles reach the lumber loaded on open rail cars by one or more of the following means: (1) through air currents and/or a partial vacuum created by movement of the train; and/or (2) through an electrostatic field which is apparently created around the moving train, which apparently consists largely of negatively charged dust particles. Such an electrostatic field apparently attracts and keeps in suspension the finely divided, positively charged iron particles, thus affording them ample opportunity to come in contact with all exposed surfaces of the wood.

After the iron dust settles on the wood, and in the presence of moisture and oxygen, the iron apparently is oxidized, solubilized, and then precipitated as ferric oxide on the surfaces of the wood; thereby, imparting objectionable discoloration, such as a dark gray, reddish or black color, to all wood surfaces exposed to such dust. Because the lumber is strapped in bundles, only the external exposed surfaces of the load are usually so stained.

Because sufficient oxygen and moisture are normally present, all wood shipped on railway cars is usually very severely iron stained when it reaches its destination. Further, because no effective chemical preventive for such staining has been available, such lumber so shipped is either wrapped in paper or plastic or shipped in closed boxcars. All of these methods are quite expensive and time consuming. In addition, when the lumber reaches destination, disposal of the paper and plastic creates a problem. Further, such materials frequently are torn during transit and the exposed wood is thence subject to prompt discoloration and/or staining.

The discovery that iron stain causes the vast majority of the discoloration of lumber (or other wood products) shipped unprotected on open railway cars is at least in part based on the following:

I. The immediate and discolored surface of a piece of Douglas fir containing severe (black) transit stain after shipment on a flat car from Eugene Oregon to Detroit, Michigan, was analyzed as follows:

A. The discoloration on the surface of the wood was dissolved in l N hydrochloric acid. The colored material was solubilized by this treatment and a portion of it was analyzed qualitatively for the presence of iron and other metals which might produce a colored precipitate. A positive test for iron only was obtained.

B. The remaining portion containing the solubilized materials causing the surface discoloration was made basic with l N ammonium hydroxide. A red precipitate of ferric hydroxide formed immediately.

2. A 1 percent solution of oxalic acid was sprayed on severely transit stained surfaces of the following species of wood: white spruce, western hemlock, southern pine, white fir, Alaska yellow cedar, incense cedar, lodgepole pine and Douglas fir. (Oxalic acid is a powerful reducing agent and is well known for its ability to solubilize to a colorless form any iron stain on wood surfaces). ln each instance, shortly after the oxalic acid solution was applied, the stained area disappeared.

SUMMARY OF THE INVENTION It is, therefore, a primary object of this invention to provide an improved method to greatly reduce the in-transit staining of green and dry wood items when shipped as articles of commerce.

Another object is the provision of an inexpensive and more reliable control of such transit stain." Although transit strain" refers primarily to iron stain, it also includes discoloration caused by other airborne particles consisting of dust, dirt, soot and oil droplets.)

Yet another object is the assurance that a load of lumber (or other wood products) arrives at its destination essentially in its original mill-bright condition.

It is a still further object to keep the lumber essentially clear while it is in transit without having to wrap same in paper or plastic or to ship it in closed boxcars.

Other objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description thereof.

Briefly speaking, the invention features the coating of exposed surfaces of either green or dry wood, prior to shipment, with compositions of matter comprised of either an antistatic agent, preferably an anionic antistatic agent, or a chemical change inhibitant for iron, preferably a chelating agent for iron, or such preferably anionic antistatic agent in combination with the chemical change inhibitant for iron, preferably a chelating agent for iron.

Wood products thus treated, such as lumber, plywood, fiberboard, particle board (chip, flake, etc.), and the like, when shipped as articles of commerce, especially by railway, are substantially protected from discoloration by atmosphericborne stains, such as caused by dirt, dust, soot, oil droplets, and/or iron particles.

was.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An exemplary of the antistatic agents, particularly the anionic antistatic agents, that may be employed in accordance with the subject invention, there are mentioned the partial esters of phosphoric acid. Such esters exhibit the structural formula:

wherein R is selected from the group consisting of straight or branched chain alkyl of from eight to 30 carbon atoms, straight or branched chain alkenyl of from eight to 30 carbon atoms, or aryl of from six to 10 carbon atoms, and R is either hydrogen or R. lt is preferred that R, and R when R=R, be a long chain alkyl or alkenyl radical of from 16 to 22 carbons.

Commercially available phosphate esters of the above type are marketed under the registered trademark of Gafstat by General Aniline & Film Corporation, New York, New York. As representative of this series, there are mentioned Gafstat AD-5l0, Gafstat AE-6l0, Gafstat AS-6l0 and Gafstat AS-7l0. All are free acids of complex organic phosphate esters, are essentially 100 percent active, have a maximum moisture content of 0.5 percent, are very pale yellow in color and have a slight pleasant odor, have a pH ranging from l .5 to 2.5 in IQ percent solution. and all are soluble at 25 C. in acetone, ethanol and xylene. The Gafstat AD-S l0, however, is only water dispersible at 25 C., whereas the AE-6l0, AS-6l0 and AS7l0 are water soluble. The AD-S l0 product, moreover, is a clear liquid which has a specific gravity of l.05l.06 at 25 C., and has an acid number (mg. KOH/gram product) to pH 7.0 of l25-l 32 and to 2nd inflection point of pH curve approximately pH 9.5 of l75l85. Corresponding values for the AE6 l 0 product are clear liquid having specific gravity of l.l0-l.l2 at 25 C.. and acid number of 70-75 and 95105, respectively; for the AS6l0 product are hazy liquid having specific gravity of l.04-l.06 at 25 C., and acid number of 95-105 and l20-l40, respectively; and for the AS-7l0 product are opaque viscous liquid having specific gravity of l.04l.06 at 25 C., and acid number of 60-75 and 92-1 12, respectively.

There is also mentioned Du Ponts "Zelec- UN (registered trademark), an anionic fatty alcohol phosphate.

An especially preferred example of an anionic antistatic agent falling within the above genus is the oleyl ether phosphate of the formula:

wherein R is either hydrogen (the monoester) or CH (CH -CH CH-(CH CH,-(the diester). lt has also been ascertained that blends ofthe aforesaid monoand diesters are effective for carrying out the aims of the present inventions. All of the immediately above derivatives are conveniently derived from oleyl alcohol, e.g., cosmetic grade oleyl alcohol.

Also envisaged are complex oleyl ether phosphates based upon a 3 to 10 mole ethylene oxide oleyl ether of phosphoric acid derived from oleyl alcohol, preferably cosmetic grade oleyl alcohol. Such complex oleyl ether phosphates are com mercially available under the trade name of Crodafos from Croda Inc. New York, New York, with Crodafos N-3 being representative thereof.

The heretofore mentioned antistatic agents according to the invention, namely, the partial esters of phosphoric acid, are conveniently employed, either in the form of the free-acid or, more preferably, the frce-acid radicals present can be neutralized, either partially or wholly. with organic or inorganic bases to form salts. Conversion of a phosphate ester free acid to an organic salt (which is the preferred) is accomplished by ad justment of the pH with a suitable organic base, for example, diethanolamine. Again, neutralization can he partial or complete. Antistatic agents thus neutralized (either partially or wholly) shall hereinafter and in the claims be designated as neutral antistats or neutral antistatic agents.

Commercially available neutral anionic phosphate ester antistats are marketed under the registered trademarks of Zelec" NE and Zelec" NK by E. l. Du Pont de Nemours, Wilmington. Del. Both are anionic fatty alcohol phosphates with a pH of from 7.0 to 7.5, the former. being water soluble, in 40 percent solution, and the latter, being water dispersible, in It) percent dispersion.

Thus, an especially preferred embodiment of the present invention comprises the neutral antistats of the formula CHr-CH'r-OH Other suitable bases for conversion of the phosphate ester free acids to organic salts comprise, in addition to the above diethanolamine, monoethanolamine. triethanolamine and morpholine.

As hereinbefore mentioned, moreover, the antistatic agents or neutral antistatic agents according to the invention are employed either alone or in combination with a chelating agent for iron. Chelation may be defined as the equilibrium reaction between a metal ion and a complexing agent, characterized by the formation of more than one bond between the metal and a molecule of the complexing agent and resulting in the formation of a ring structure incorporating the metal ion. Thus, chelation is an essentially chemical process which involves the formation of a complex usually heterocyclic ring compound containing a metal cation. A chelating agent is a compound capable of forming such complex; and a chelating agent for iron is a compound capable offorming such complex with iron as the metal cation. The molecule, ion or group bound to the metal cation is known as a ligand. In the practice of the instant invention, the chelating agents preferably have two or more such points of attachment, and such a chelating agent is referred to as a polydendate ligand.

The chelating agents for iron which may be used in the practice of the instant invention include the known alkanol amines, such as monoethanolamine, diethanolamine, triethanolamine and morpholine. An important characteristic of the preferred chelating agents for iron according to the invention is that same react upon drying with some unknown component or components of most commercially important woods and produce colored reaction products, which are thought to be dyes. The color varies with the species of wood involved but usually is either yellow, brownish-yellow, reddish-brown or orange and develops usually within thirty minutes after application to the wood substrate. (The color reaction can be speeded, in some instances at least, by further making the wood more acidic). The color largely disappears after two to four days exposure to sunlight, and for this reason it is a good visual indicator during this period to indicate that the wood has been treated. The dye so formed appears to be stable to heat and incandescent light and is thought to be unstable to the ultraviolet portion of sunlight. Woods of high acidity (most species of wood, especially the commercially important softwoods, i.e., Douglas fir, southern pine, hemlock, white fir, etc., are at least somewhat acidic) cause the color to develop more rapidly and usually more intensely.

Furthermore, the chelating agents for iron which may be used in the practice of the instant invention are preferably tantamount to those organic bases employed for the neutralization of those heat stable antistatic agents comprised of the partial esters of phosphoric acids according to the invention. However, as previously indicated, such chelating agents for iron may be employed alone, as well as in combination with an antistatic agent, preferably an anionic antistatic agent, or in combination with a neutral antistat, preferably a neutralized anionic antistatic agent.

The product found to be most useful in practicing this invention is sold by the Specialty Products Division of General Mills Company, Minneapolis, Minnesota, under the registered trademark of RepulS. RepulS has been ascertained to be a neutral diethanolamine salt of oleyl ether phosphate, a partial ester of phosphoric acid, with this material comprising approximately 90 percent of the product. Such determination was based upon, inter alia, examination by infrared spectroscopy. The submitted sample (salve consistency) was examined by infrared spectroscopy and its absorption spectrum recorded on the spectrogram which is illustrated in FIG. 1 of the drawing. Although this spectrum does not appear to represent the absorption characteristics of a pure substrate (less than 95 percent purity), it does possess the principle absorption feature of an alkanol amine salt of an oleyl ester of phosphoric acid (monoor diester of phosphoric acid). Confirmatory evidence supporting the aforesaid characterization was an elementary analysis indicating negative halogens and sulfur responses and positive nitrogen and phosphorus responses. Moreover, a steam distillation of the sample separated approximately lO percent of a volatile liquid which was indicated by infrared spectroscopy to be the fatty alcohol, 1- octyl alcohol. Such spectrogram of this steam distillate is represented as FIG. 2 of the drawing. Still further, infrared spectroscopy of the free-acid form of RepulS (nitrogen as N, 0.003 percent) yielded the infrared absorption spectrum illustrated in FIG. 3 of the drawing. The absorption features of this spectrum (FIG. 3) are characteristic of an oleyl ester of phosphoric acid (acid form). Absorption bands indicate that this ester is not neutralized with an ethanol amine. The amount of oleyl ether phosphate, diethanolamine salt, calculated from the nitrogen content, is about 0.1 percent. Moreover, the neutral RepulS is constructed from stoichiometric proportions of acid and base.

The properties of RepulS which make it so useful in the present invention are: (1) It is both an anionic antistatic chemical and also has chelating ability for iron. (2) It is only slightly soluble in water, and thereby, resists leaching from the wood. (3) it has a high boiling point and therefore is relatively nonvolatile. (4) It reacts upon drying with some unknown component or components of most commercially important woods and produces a colored reaction product, which is thought to be a dye. The color is variable but is usually yellow, brownish-yellow, reddish-brown or orange and develops usually within 30 minutes after its application to the wood. (The color reaction can be speeded, in some instances at least, by further making the wood more acidic.) The color largely disappears after two to four days exposure to sunlight, and for this reason it is a good visual indicator during this period to indicate that the wood has been treated. The dye so formed appears to be stable to heat and incandescent light and is thought to be unstable to the ultraviolet portion of sunlight. Woods of high acidity cause the color to develop more rapidly and usually more intensely. it is believed that the diethanolamine portion of RepulS is the part which produces the color reaction with wood. (It is known to us that such materials as monoethanolamine, diethanolamine, triethanolamine and morpholine also react with such woods to produce similar colors. These colors also are apparently unstable when exposed to sunlight, or possibly their color is masked by darkening of the wood itself when it is exposed to sunlight). As previously indicated, the color reaction with wood is an important characteristic of the preferred chelating agents for iron according to the invention.

Such materials as these are thought to react with phenolic moieties present in such woods.

Because a reaction does occur with some components of wood, it appears that this property would further make RepulS more resistant to leaching from the wood. This property appears especially important for lumber in-transit because other well-known chelating agents are usually more water soluble and volatile and therefore, would not be as resistant to leaching. (5) It is highly surface active and therefore wets the wood surfaces readily. (6) It is soluble in such volatile materials as isopropanol, ethanol, ethyl acetate and benzene. The foregoing means that the treatment will dry quickly and that the RepulS will be rapidly insolubilized by reacting with the wood. The chemical, therefore, should remain on the wood even when it is exposed to rain shortly after its application. (7) It is readily compatible with many of the well-known chelating agents, ultraviolet absorbers, wood preservatives, water repellents, pigments, end paints or end sealers, and fire retardants; thus, making it possible to formulate a variety of multipurpose solutions for treatment of wood. (8) Being highly soluble in isopropanol and ethanol assures that it can be handled conveniently under severely cold weather conditions, without the necessity for keeping it heated. (9) Lastly, being anionic, it principal mode of action in preventing iron staining of wood while it is in transit on a railroad, other than its chelation properties, is thought to be related to its ability to repel iron-carrying and negatively charged dust particles, which must contact all surfaces surrounding railway cars in motion. Thus, by repelling such electrostatic, iron-carrying dust particles, the iron particles are prevented from being carried a sufficient distance up from the road bed to reach the wood loaded on the cars.

The control method of the instant invention comprises the coating of exposed surfaces of either green or dry species of wood with antistatic or neutral antistatic agents (preferably anionic antistats or neutral antistats) and/or chelating agents for iron by brush, dip or spray methods, and thence said treated surfaces are permitted to dry, preferably under ambient atmospheric conditions. Upon drying, those substrates treated with compositions of matter comprised of a woodreactive chelating agent for iron exhibit the hereinbefore mentioned color reaction phenomenon, which usually yellow, brownish-yellow, reddish-brown or orange color subsequently largely disappears.

The foregoing chemicals, especially RepulS (or its use in combination with various alkanol amines, such as monoethanolamine, diethanolamine, triethanolamine and morpholine, or in combination with buffering materials such as borax and/or soda ash to control the pH of the resulting solutions so that same remain on the alkaline side), are advantageously applied when prepared as a diluted solution in the proper inert solvent or as a stable dispersion in the proper inert solvent or as a stable dispersion in the proper inert diluent. lsopropanol is the preferred diluent for RepulS based compositions, and aqueous dispersions thereof are remarkably shelf stable.

Unstained lumber (or other wood products) thus treated and shipped as articles of commerce, either by ship, plane or especially by railway, are virtually assured of arriving at destination in essentially a mill-bright condition,

Representative of the various softwood species that may be treated according to the invention are Douglas fir, white spruce, white fir, lodgepole pine, hemlock (western and eastem), Alaska yellow cedar, Ponderosa pine, sugar pine and southern pine. and representative of the various hardwood species are red oak, white oak, cottonwood, pecan and hickory.

In order to further illustrate the present invention and the advantages thereof, the following specific examples are given, it being understood that the same are merely intended to be illustrative and in no wise limitative.

EXAMPLE I A solution consisting of percent RepulS, l5 percent isopropanol and 80 percent water (by weight) was prepared by mixing at room temperature. The dispersion was used to spray A of the surface of green and kiln dried 2 inch X 4 inch X 12 inch samples of southern pine, Douglas fir, and hemlock wood. The samples were exposed horizontally for 6 weeks within feet of a mainline railroad track. Examination of these samples at the end of the test period indicated that the treated surfaces were only slightly discolored in comparison to the unsprayed surfaces.

EXAMPLE 2 Three samples each of kiln dried southern pine wood measuring 1 inch x 4 inch X l2 inch were dipped for 5 seconds to 5% their length in each of the solutions, or dispersions as the case may be, indicated in table I. The samples were allowed to dry for minutes before finely divided iron powder (Reagent grade) was sprinkled over the entirety of one flat surface. The samples were exposed outside in a horizontal position for one week, following which, each was examined for the presence of iron stain on both the treated and untreated surfaces. Relative control of iron stain, in comparison to that obtained on the untreated surfaces, is shown in table 2.

3 Good 4 Very Poor 5 Very Poor 6 Poor 7 Good 8 Good 9 Good EXAMPLE 3 Two kiln dried Douglas fir wafers measuring inch X 2% inch X 5 inch in size were given a 2-second dip in a dispersion consisting of 10 percent RepulS and 90 percent water. One wafer consisted entirely of heartwood and the other contained both heartwood and sapwood. One-third only of the length from each end was dipped as above; thereby, leaving the cen tral A: of the length of each wafer as an untreated control. Each wafer was allowed to air dry to 30 minutes before finely divided iron powder (Reagent Grade) was sprinkled over the entirety of one flat surface. The wafers were then placed in a polyethylene tent in which steam was slowly emitted to warm and humidify the air. Following 25 minutes of such exposure, the wafers were removed and examined for the presence of iron stainv The relative condition of the wafers after such treatment and exposure was indicated by the fact that the treated surfaces still bore the iron sprinklings but were devoid of iron stain, whereas the untreated controls were badly iron stained, the sapwood to a lesser extent than the heartwood.

EXAMPLE 4 A test kit was prepared which contained l8 samples of kiln dried wood specimens l inch X 4 inch X 12 inch in size. Nine samples each of southern pine and Douglas fir were included. The former consisted entirely of sapwood and the latter contained only heartwood. One-half of each sample was dipped for 5 seconds in the solutions described in table 3. The test kit was fastened on top of a flat car loaded with lumber and was allowed to travel with the car from Eugene, Oreg., to Baytown, Missouri. At the end of this trip, the samples were rated for surface discoloration with results as shown in table 4.

TABLE 3.-COMPOSITION OF SOLUTIONS USED IN EXAMPLE 4 Solution Number 1 2 3 Chemical, weight percent:

Soda ash (Na Coa) RepulS Monoethanolamine I 'Irlethanolamine 3M Fluorocarbon FC-134 L Uvlnul D-49 Water s L l Manufactured by Minnesota Mining & Manufacturing Company, an oleophobic additive.

Z 2,2-dihydroxy-4,4-dimethoxybenzophenone.

TABLE 1.COMPOSITION OF SOLUTIONS USED IN EXAMPLE 2 Solution Number l 1 2 3 4 Chemical, weight; percent: Soda ash (Na C0 RepulS Monoethanolamine. 3M Fluorocarbon FC Isopropyl alcohol 7 Water I 1 Manufactured by Minnesota Mining & Manufacturing Company. an oleophobic additive TABLE 2 TABLE 4 RELATIVE CONTROL OF IRON STAIN OBTAINED RELATIVE CONTROL OF IRON STAIN OBTAINED WITH SOLUTIONS OF EXAMPLE NO. 2 WITH SOLUTIONS OF EXAMPLE 4 Solution Number Relative Control of Iron Stain Southern Pine Douglas Fir Solution No sapwood Heartwood l Poor 2 Fair l Very Good Very Good 2 Very Good Poor 3 Very Good Very Good 4 Good Fair 5 Poor Very Poor 5 Fair Very Poor 7 Fair Very Poor 8 Very Good Fair 9 Very Good Fair EXAMPLE 5 Approximately 40,000 board feet of green Douglas fir lumber were loaded on Flat Car No. NP 62435 at Seneca Sawmill Company, Eugene, Oreg. The load consisted of 8 bundles or bunks of such lumber of approximately equal size. After the car was loaded and ready for shipment, all external surfaces of the load, except the exposed side of one bundle, were given a spray treatment with a solution composed of 10 percent RepulS, 10 percent monoethanolamine, 40 percent isopropyl alcohol and 40 percent water. The untreated bundle served as a control. The car was treated and shipped to Metropolitan Lumber Company, Milwaukee, Wis. on Nov. 13, 1968. It arrived in Milwaukee on Nov. 26, 1968, and was thoroughly inspected for any evidence of transit stains. Except for some scattered stains on a few boards on top of the load and several streaks of very light stain (apparently caused by water draining from the top) on the side of the untreated bundle, no stains or discolorations of any nature were visible on any surfaces of the lumber. Not only was the treated lumber free from stain,

but also the untreated portion and dunnage were in equally ex-' cellent condition, which phenomenon was completely surprising and unexpected.

EXAMPLES 6 and 7 Two other carloads of similar materials were treated at the same time as Car No. NP 62435. One of these cars (No. GN 65180) was shipped to Cotton-Hanlon, lnc. Odessa, NY. The other one (No. GN 65 l 16) was shipped to Harold C. Mutziger Lumber Company, Oklahoma City, Okla. Only the bottom 4 bundles were treated on these cars. Thus, the top 4 bundles served as controls. The untreated bundles on these cars, as well as the treated bundles, also arrived at destination in almost perfect condition, with only slight evidence of transit stain or discoloration. Again, the unusually good condition of the untreated bundles was completely unexpected. Because no previous instance is known where untreated material of similar nature was shipped in this manner and arrived at destination in such good condition, one is forced to conclude that the treatment applied to the treated bundles was also protecting the untreated bundles through some unexpected actron.

Further investigation of possible phenomena which might have caused the treatment on the treated bundles to also protect the untreated bundles leads one to the conclusion that a negative electrostatic atmosphere of dust particles must be developed around a moving railway car which attracts and holds in suspension positively charged iron particles, with these particles, under normal conditions, being brought in contact with the wood so that iron stain might occur on the wood. lf such an atmosphere exists around a moving train, it further appears reasonable that, e.g., RepulS, being an antistat of strong anionic nature, must dissipate this negative charge as it develops, so that the iron particles on the road bed, and those produced from interaction between the wheels and rails and from wear on the brakeshoe linings as the train moves, do not rise to sufficient height in local air currents to reach the surfaces of the material loaded on the cars.

If the foregoing is a correct explanation of the results obtained from example 4, it should be obvious that such materials as RepulS applied in various ways or to railway cars and railway road beds would probably protect other products as well from such transit stains and discolorations.

EXAMPLE 8 Approximately 40,000 board feet of green Douglas fir lumber were loaded on a flat car at Eugene Oreg. After the car was loaded and ready for shipment, all external surfaces of the load were given a spray treatment with a solution comprised of 10 percent RepulS, 50 percent water and 40 percent isopropyl alcohol. The car thus treated was shipped to Oklahoma City, Oklahoma, Upon arrival the car was thoroughly inspected for any evidence oftransit stains. The load on the car was clean.

EXAMPLE 9 Approximately 40,000 board feet of green Douglas fir lumber were loaded on a flat car at Eugene Oreg. After the car was loaded and ready for shipment, all external surfaces of the load were given a spray treatment with a solution comprised of 5 percent RepulS, 10 percent monoethanolamine, 45 percent water and 40 percent isopropyl alcohol. The car thus treated was shipped to Kansas City, Missouri. Upon arrival the car was thoroughly inspected for any evidence of transit stains. The load on the car was clean.

EXAMPLE 10 Approximately 40,000 board feet of green Douglas fir lumber were loaded on a flat car at Eugene Oreg. After the car was loaded and ready for shipment, all external surfaces of the load were given a spray treatment with a solution comprised of 10 percent RepulS, 10 percent monoethanolamine, 40 percent water and 40 percent isopropyl alcohol. The car thus treated was shipped to Buffalo, NY. Upon arrival the car was thoroughly inspected for any evidence of transit stains. The load on the car was clean.

EXAMPLE I] Approximately 40,000 board feet of green Douglas fir lumber were loaded on a flat car at Eugene, Oreg. After the car was loaded and ready for shipment, all external surfaces of the load were given a spray treatment with a solution comprised of 10 percent Crodafos N-3 Neutral, l0 percent monoethanolamine, 40 percent water and 40 percent isopropyl alcohol. The car thus treated was shipped to La Porte, lnd. Upon arrival the car was thoroughly inspected for any evidence of transit stains. The load on the car was nearly clean, but there being present scattered discolorations ascertained to be brownish water streaks.

EXAMPLE l2 Approximately 40,000 board feet of green Douglas fir lumber were loaded on a flat car at Eugene, Oreg. After the car was loaded and ready for shipment, all external surfaces of the load were given a spray treatment with a solution comprised of 10 percent RepulS, l0 percent monoethanolamine, 1 percent soda ash, 39 percent water and 40 percent isopropyl alcohol. The car thus treated was shipped to Chicago, Ill. Upon arrival the car was thoroughly inspected for any evidence of transit stains. The load on the car was clean.

EXAMPLE 1 3 Approximately 40,000 board feet of green Douglas fir lumber were loaded on a flat car at Eugene, Oreg. After the car was loaded and ready for shipment, all external surfaces of the load were given a spray treatment with a solution comprised of 10 percent Gafstat AB 610, 10 percent monoethanolamine, 40 percent water and 40 percent Ell isopropyl alcohol. The car was then shipped to Detroit, Mich. Upon arrival the car was thoroughly inspected for any evidence of transit stains. The load on the treated car was clean.

EXAMPLE l4 Five samples each of kiln dried Douglas fir wafers measuring V4 inch X 2% inch X 5 inch in size were dipped for approximately one second to 5% their length in a solution comprised of percent of Du Pont's Zelec" NE anionic fatty alcohol phosphate (up to 40 percent water soluble), 50 percent water and 40 percent isopropyl alcohol. The samples were allowed to dry overnight before finely divided iron powder (Reagent grade) was sprinkled over the entirety of one flat surface. The color (yellow) reaction with wood was in evidence upon drying. The samples were then placed in a plastic treatment chamber into which steam was slowly introduced to warm and humidify the air. Following overnight exposure, the samples were removed and examined for the presence of iron stain. The relative condition of the samples after such treatment and exposure was indicated by the fact that the treated surfaces still bore the iron sprinklings but the control of iron stain was good, whereas the untreated control ends were badly iron stained.

EXAMPLES Five samples each of kiln dried Douglas fir wafers measur ing inch X 2% inch X 5 inch in size were dipped for approximately one second to Be their length in a solution comprised of 10 percent of Du Pont's Zelec" NK anionic fatty alcohol phosphate (water dispersible), 50 percent water and 40 percent isopropyl alcohol. The samples were allowed to dry overnight before finely divided iron powder (Reagent grade) was sprinkled over the entirety of one flat surface. The color (yellow) reaction with wood was in evidence upon drying. The samples were then placed in a plastic treatment chamber into which steam was slowly introduced to warm and humidify the air. Following overnight exposure, the samples were removed and examined for the presence of iron stain. The relative condition of the samples after such treatment and exposure was indicated by the fact that the treated surfaces still bore the iron springlings but the control ofiron stain was good, whereas the untreated control ends were badly iron stained. Moreover, the instant formulation was more resistant to leaching than the formulation of example 14, presumably due to the water dispersibility rather than solubility thereof.

EXAMPLE 16 Five samples each of kiln dried Douglas fir wafers measuring A inch X 2% inch X 5 inch in size were dipped for approximately one second to 9% their length in a solution comprised of IO percent of Du Pont's Zelec" UN, 50 percent water and 40 percent isopropyl alcohol. The samples were allowed to dry overnight before finely divided iron powder (Reagent grade) was sprinkled over the entirety of one flat surface. No color reaction with the wood was in evidence upon drying, presumably due to the fact that Zelec UN is an acid form anionic fatty alcohol phosphate, rather than a neutral. The samples were then placed in a plastic treatment chamber into which stream was slowly introduced to warm and humidify the air. Following overnight exposure, the samples were removed and examined for the presence of iron stain. The relative condition of the samples after such treatment and exposure was indicated by the fact that the treated surfaces still bore the iron sprinklings but only very slight iron stain was evident, whereas the untreated control ends were moderately iron stained.

EXAMPLE [7 Five samples each of kiln dried Douglas fir wafers measuring V4 inch X 2% inch X 5 inch in size were dipped for approximately one second to 9.; their length in a solution comprised of IO percent of Du Pont's Zelec DP dispersion of complex organic cationic polymers, 50 percent water and 40 percent isopropyl alcohol. The samples were allowed to dry overnight before finely divided iron powder (Reagent grade) was sprinkled over the entirety of one flat surface. No color reaction with the wood was in evidence upon drying. The samples were then placed in a plastic treatment chamber into which steam was slowly introduced to warm and humidify the air. Upon evaluation after 25 minutes exposure in the test chamber, the treated portion was already covered with iron stain, whereas the untreated portion had just begun to stain. The samples were subsequently exposed overnight and reexamined, at which time the entire surface, both the treated and untreated portions, was black with iron stain.

EXAMPLE 18 Five samples each of kiln dried Douglas fir wafers measuring 5 inch X 2% inch X 5 inch in size were dipped for approximately one second to their length in a solution comprised of 10 percent of Du Pont's Zelec" DX dispersion of complex organic cationic polymers, 50 percent water and 40 percent isopropyl alcohol. The samples were allowed to dry overnight before finely divided iron powder (Reagent grade) was sprinkled over the entirety of one flat surface. No color reaction with the wood was in evidence upon drying. The samples were then placed in a plastic treatment chamber into which steam was slowly introduced to warm and humidify the air. Upon evaluation after 25 minutes exposure in the test chamber, the treated portion was already covered with iron stain, whereas the untreated portion had just begun to stain. The samples were subsequently exposed overnight and reexamined, at which time the entire surface, both the treated and untreated portions, was black with iron stain.

EXAMPLE 19 Two samples each of kiln dried Douglas fir wafers measuring V4 inch X 2% inch X 5 inch in size were dipped for approximately one second to k their length in a solution comprised of 5 percent thiourea, 55 percent water and 40 percent isopropyl alcohol. The samples were allowed to dry overnight before finely divided iron powder (Reagent grade) was sprinkled over the entirety of one flat surface. The samples were then placed in a plastic treatment chamber into which steam was slowly introduced to warm and humidify the air. Upon evaluation after 25 minutes exposure in the test chamber, the treated portion was already covered with iron stain, whereas the untreated portion had just begun to stain. The samples were subsequently exposed overnight and reexamined, at which time the entire surface, both the treated and untreated portions, was black with iron stain.

EXAMPLE 20 Two samples each of Kiln dried Douglas fir wafers measuring /4 inch X 2% inch X 5 inch in size were dipped for approximately one second to V; their length in a solution comprised of 10 percent monocthanolamine, 50 percent water and 40 percent isopropyl alcohol. The samples were allowed to dry overnight before finely divided iron powder (Reagent grade) was sprinkled over the entirety of one flat surface. The samples were then placed in a plastic treatment chamber into which steam was slowly introduced to warm and humidify the air. Following overnight exposure, the samples were removed and examined for the presence of iron stain. The relative condition of the samples after such treatment and exposure was indicated by the fact that the treated surfaces still bore the iron sprinklings but the control of iron stain was moderate, whereas the untreated control ends were very heavily iron stained.

EXAMPLE 21 Two samples each of kiln dried Douglas fir wafers measuring as inch X 2% inch X 5 inch in size were dipped for approximately one second to it their length in a solution comprised of 5 percent thiourea, l percent monoethanolamine, 45 percent water and 40 percent isopropyl alcohol. The samples were allowed to dry overnight before finely divided iron powder (Reagent grade) was sprinkled over the ,entirety of one flat surface. The samples were then placed in a plastic treatment chamber into which steam was slowly introduced to warm and humidify the air. Following overnight exposure, the samples were removed and examined for the presence of iron stain. The relative condition of the samples after such treatment and exposure was indicated by the fact that the treated surfaces still bore the iron sprinklings but the control of iron stain was complete in one instance and near perfect in the other, whereas the untreated control ends were very heavily iron stained.

It will be appreciated that the active ingredient(s) comprising the compositions of matter useful according to the invention may vary over considerably wide limits, with concentrations thereof being dictated by many factors as, for example, the wood itself intended to be treated, the chemical nature of the active ingredient(s), the prospective rigors of transit (both geographical and environmental), and the like. Generally speaking, however, it has been found that concentrations of active ingredient(s) of from between about percent to about 30 percent by weight will suffice in most, if not all instances. in any event, such concentrations are readily ascertainable by the ordinarily skilled artisan per any given intended application. A suitable application rate for the compositions of the invention is about 5 to 6 gallons of solution per each railway car loaded with about 40,000 board feet of lumber.

As previously indicated, one key to the instant invention resides in the concept of dissipating accumulated static electrical charges, as they are developed. More particularly, as, for example, a negative electrostatic atmosphere of dust particles is developed around, e.g., a moving railway car, which atmosphere tends to attract and hold in suspension positively charged iron particles (which are thence normally brought into contact with the wood), the antistatic treatment according to the invention effects repulsion of such negatively charged dust particles, which particles bear the positively charged (or possibly uncharged) iron particles. Thus, the iron contaminant is prevented from rising to heights sufficient to enable same to contact the surfaces of the material desired to be protected. Accordingly, essentially no iron stain is developed in transit.

Another key to the instant invention resides in the concept of rendering the iron particles substantially impervious to chemical change, such as by using according to the invention a chelating agent for iron in the treatment of the wood. in this respect, it will be appreciated that the solubilized reaction products of iron, when precipitated or otherwise deposited on the surfaces of the wood, are primarily responsible for imparting the transit stain" thereto. An example of such objectionable chemical change phenomenon is the oxidation of iron by means of the oxygen and moisture present in the atmosphere and/or in or on the wood, solubilization of the reaction product and subsequent precipitation thereof as ferric oxide (which usually imparts a dark gray or black color) on the surfaces of most species of wood. Therefore, it will also be appreciated that chemical change inhibitants, such as chelating agents, anticorrosion agents, antioxidants and the like, which exert a certain degree of protective action on the iron and which are compatible with the substrate desired to be protected are advantageously employed in the treatment of the invention. Particularly advantageous are those agents which exhibit the heretofore mentioned color reaction with wood either upon contact and/or upon drying and which are lasting under severe conditions of leaching action by water and-exposure to natural weathering, such as are encountered during the rigors of transit.

One of the reasons why neutral antistats of the RepulS type are preferred in practicing the invention is that such materials are at the same time strong anionic antistatic agents, good chelating agents for iron and good corrosion inhibitors, and are water insoluble upon drying. This in spite of the fact that both the acidic and alkaline portions of the macromolecule are somewhat corrosive in and of themselves; also in spite of the fact that it is believed that the macromolecule reverts to such free acid and free base moieties upon drying on the wood without deleterious results.

Moreover, and also as previously indicated, the compositions of matter useful in practicing the treatment of the invention can be advantageously comprised of [in addition to the active ingredient(s) thereof] compatible ultraviolet absorbers, wood preservatives, water repellents, pigments, antimicrobials, end paints or end sealers, flame retardants and pH control agents. As representative of such materials to be added, there are mentioned millbrite'UA formulation of microcrystalline wax (39"/,), triethanolamine (l.4"/,,), stearic acid (1.8%,), sodium pentachlorophenate (2.0%,) and water (55.8%,). See USP 3,281,318. (Chapman Chemical Co.), a solvent soluble a water and pigment suspension, an o/w wax emulsion-plus-pigments in water (preferably a 60 percent paraffin wax emulsion), a stable liquid sapstain concentrate effective against a broad spectrum of micro-organisms that attack lumber and veneers such as Permatox-lOOHSee USP 3,305,298.) (Chapman Chemical Co.), and the antimicrobial water repellent emulsions of our copending application, Ser. No. 800,000 filed Feb. 14, 1969.

It will be appreciated that the treatment of the invention is applicable to a variety of products or materials other than wood to afford same protection from transit stains, primarily iron stain, and discolorations.

A variant of the invention worthy of consideration is derived from the realization that most commercially important woods are at least somewhat acidic. Thus, it has been additionally found that neutralization of the natural acidity of woods with any suitable organic or inorganic base, or alkaline agent generally, will render such woods at least temporarily protected from transit stain when shipped as articles of commerce. Generally speaking, however, such protection is indeed ephemeral, as most alkaline agents, per se, are quite subject to even moderate conditions of leaching action, as, for example, normal rainfall. Nevertheless, and since the alkaline agents contemplated are chemical change inhibitants for iron at least to some extent, it logically follows that in some instances the rigors of transit would be such as to warrant shipment of items thus treated while being reasonably assured of having same arrive at destination in essentially unstained conditions, e.g., transit through zones of mild weather, with little or no rainfall, and which are geographically or topographically nearly homogeneous. Suitable alkaline agents for the aforesaid purpose, and which also must be compatible with the wood or item proposed to be shipped, comprise soda ash and the amine soaps, as, for example, those resulting from the reaction of fatty acids such as stearic and oleic with amines such as monoethanolamine. Neutralization is conveniently accomplished by adjustment of the pH of the wood with the alkaline agent.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the same is not to be limited to the specific embodiments thereof, except as defined in the appended claims.

What is claimed is:

l. A composition for application to wood items to control in-transit discoloration by atmospheric-borne stains, primarily iron stain, consisting essentially of and b. about 5.0 weight percent of monoethanolamine, c. about 2.6 weight percent of soda ash (Na CO d. about 15.0 weight percent isopropyl alcohol, and

e. about 7244 weight percent water. 

